Both sides of 20mm wide white sew-on and self-adhesive velcro type tape.
One side is to sew onto the fabric and the other is adhesive backed to attach to the header batten. I also use a stapler with the sticky side for extra strength. See photos.
Note: this is priced per 50 cms or per 75 cms. Order just how much you need by choosing a length and changing quantity in cart. Multiple orders will be sent in one continuous length.